In the field of this invention, there are several factors which are important:                1. Precision of the cut with respect to position, angle, and straightness        2. Quality of the cut such that there is minimal tear out (splintering) of the workpiece        3. Ability to cut a wide range of angles from parallel rip cuts to 90 degree cross cuts        4. Ability to cut workpieces of different sizes and shapes        5. Make repetitive cuts to a series of identical workpieces with consistent accuracy        6. Hold and support the workpiece solidly without damaging it        7. Safe to use and complements other safety devices normally used with the cutting tool        8. Easy to use with a quick set-up and tear-down time        9. Reasonable size, weight, and shape for handling and storing        10. Competitive cost to manufacture the deviceTo varying degrees, the prior art has taken on many different configurations to address these needs. The current state of technology of the known configurations, however, has focused on subsets of these important elements. Opportunities exist to improve upon the prior art to better answer these needs. Given the nature and function of this invention, it is important to look at prior art that encompasses taper cutting, straight-line cutting, and the means of how these are achieved.        
U.S. Pat. No. 2,032,976 issued to Carter describes an adjustable taper ripping jig which uses two arms hinged together on one end and an adjusting and locking mechanism on the other end to set an angle. The arm that guides the workpiece also has an adjustable end stop. The jig is used in conjunction with a standard fence accessory which is parallel to the cutting plane on the table surface of the cutting tool. The fact that variations of this design are still prevalent in the marketplace is a testament to its utility and value; however, it does have limitations. Unfortunately, an operator using this jig must put pressure from the side and top to keep the workpiece against the jig and table top, and the jig against the fence. This potentially places the operator in a dangerous position while cutting. It also makes it challenging to produce a quality cut. The range of angles that can be cut and the size and shape of the work pieces that can be cut are both limitations as well. It can also be difficult to determine exactly where the taper cut will be along the workpiece.
U.S. Pat. No. 4,002,329 issued to Petrowski describes a different guide device for making taper cuts. This configuration uses a guide member which slides along the guide slot of a cutting tool's table surface. A workpiece holder is attached to the guide member using adjustable connections which can be fixed in place to create an angle. The usage of the guide slot does isolate the guide member from significant lateral movement. Unfortunately, the way in which the guide slot is used limits the width of workpiece that can be cut. It also limits the range of angle that can be cut. No precise means of fitting the guide member to the exact size of the guide slot is specified. Without a precise fit, the quality of the cut on the workpiece will be compromised. Furthermore, if a runoff table is used in conjunction with the cutting tool's table surface, this require a longer than usual slot in the surface of the supporting table to allow the device to cut longer boards. Similar to the U.S. Pat. No. 2,032,976 design, this device also lacks a means of positively holding the workpiece to the workpiece holder. Additionally, both designs only have an end stop. This requires the operator to apply side pressure to the workpiece during cutting as discussed previously.
U.S. Pat. No. 4,002,329 issued to Larsson describes a woodworking guide accessory for making taper cuts by using a design similar to the U.S. Pat. No. 2,032,976 design. The most significant improvement with Larsson's configuration is that the workpiece is positively and precisely clamped to the device. It also has handles which allows the operator to more safely guide the devise and the workpiece during cutting. However, this design has some of the same limitation of the two previous designs. Once again the range of angle that can be cut in the workpiece is constrained. Additionally, since the clamps elevate the workpiece from the cutting tool's table surface, there is more opportunity for the workpiece to experience tear-out during the cutting process. Furthermore, the materials and component parts required to manufacture an embodiment of the device does increase its cost.
U.S. Pat. No. 4,164,882 issued to Mericle is a guide apparatus which is designed to make straight (rip) cuts in a workpiece which can have an irregular shape excluding the ends. This design uses guide member which can ride in the cutting tool's table surface guide slot or along a moveable guide slot that clamps to the table surface. The workpiece is held in place to the device by utilizing “conical point members mounted upon spindles” which attach to the ends. If the device is used with one of the table surface guide slots, it will have the same challenges as discussed previously regarding the quality of the cut if the guide is not precisely fit to the table slot and it may interfere with a runoff table when making long cuts. If the adjustable guide slot is utilized, the precision of the fit can be improved greatly. However, the workpiece will then be elevated from the cutting tool's table surface which can reduce the quality of the cut as discussed previously. Furthermore, given the method of fixing the workpiece to the device, the workpiece will be damaged on the ends. This limits the device to cutting workpieces with unfinished ends which must be subsequently trimmed if the appearance of the workpiece is important.
U.S. Pat. No. 5,113,734 issued to Mahler devises another guide configuration to cut straight (rip) cuts in a work piece that has two uneven edges. This device is used in conjunction with a fence accessory on the table surface of the cutting tool. The design uses two push stops along the side to support the uneven edge and pin points on one end to help secure the end to the device. The main limitations of this design are the need to place pressure to the side of the workpiece and guide. The pin points also create damage to the workpiece end.
U.S. Pat. No. 5,823,084 issued to Ramey for a guide configuration to produce straight line cuts in a workpiece. The device uses a board with toggle clamps to secure the workpiece. A second board is fixed over the cutting tool to act as a guide for the board with the workpiece. A fence accessory can then be position to guide the board with the workpiece from the other side. There are limitations with this design. The maximum width of the workpiece that can be cut is dependent on the fixed width of the device. When cutting workpieces of different thicknesses, the toggle clamps must be adjusted each time. Also, depending on the fixed spacing of the toggle clamps, the operator may be unable to clamp a short length workpiece.
U.S. Pat. No. 5,918,520 issued to Whitcomb is another version of a straight line saw guide. This device is similar to the previous design by Ramey; except, it provides a width adjustment. However, given the positioning of the toggle clamps, this design is less tolerable of irregularly shaped workpieces. Since it uses one of the table surface guide slots, it will have the same challenges as discussed with U.S. Pat. No. 4,164,882. This may impact the quality of the cut if the guide is not precisely fit to the table slot, and it may interfere with a runoff table if one is used with the cutting tool. As mentioned with the Ramsey design, the toggle clamps must also be adjusted for different workpiece thicknesses.
U.S. Pat. No. 7,000,519 issued to Weinstein describes a clamping device that is used in conjunction with a reference board and the workpiece to provide guidance in making straight line cuts. It also has a shim arm to help support the workpiece to compensate for the lower clamp surface thickness. This design provides a lower cost alternative compared to the other designs for cutting straight line cuts. The two main limitations are the potential cut quality issues from the work piece being elevated from the cutting tool's table surface and the inability to cut more irregularly shaped workpieces.
U.S. Pat. No. 5,275,074 issued to Taylor describes a slide device for the guide member slot of a cutting tool's table surface. This design utilizes wedges that will expand the sides of the slide to fill the gap with the slot when a compressive force is applied from the top and bottom using a machine screw. U.S. Patent Application Publication US2008/0083311 A1 describes an adjustable guide by inventor Wang. In this design, a wedging action is also used such that a compressive force on the ends of the stacked guide member pieces expands the width of the guide to match the slot width. Both designs provide an adequate means of more precisely matching the guide member width to the slot width. However, neither guide member design is particularly suitable for locking and unlocking the guide to a cutting tool's table surface guide slot while the guide is attached to a larger jig. Also, depending on the materials used and the method of manufacturing, both designs can be expensive to produce.
With the limitations highlighted in the current art, there is a definite need for a better design configuration which provides precise and quality cuts over a larger range of workpiece sizes and shapes with a cost-effective construction.